Stacked family molding and subsequent assembly process

ABSTRACT

The subject invention relates to a precision injection molding of multi-piece parts and the subsequent handling and assembly of those parts produced from the mold. In an exemplary embodiment, a surgical suture package with a top part and a bottom part is molded and assembled. In such a method and system, the top parts and bottom parts are first molded utilizing a family mold and then are transferred to a stacker. The stacker is able to stack the top part and bottom part on top of one another on a pallet. The parts are then transported to a welder in order to weld the top part and bottom part together. The completed surgical suture packages are then transferred to a magazine for storage and shippage.

RELATED APPLICATIONS

This application is a divisional application of U.S. Nonprovisionalpatent application Ser. No. 11/695,868 filed on Apr. 3, 2007, now U.S.Pat. No. 7,950,127 which is hereby incorporated by reference in itsentirety, and which is a divisional application of U.S. Nonprovisionalpatent application Ser. No. 10/769,3103, filed on Jan. 30, 2004, nowU.S. Pat. No. 7,214.286.

BACKGROUND OF INVENTION

The subject invention relates to injection molding machines that areable to mold at least two separate distinct parts at the same time andrelates, in particular, to methods and systems for retrieving andassembling the at least two molded parts into a completed product. Theuse of family molds have become common in the production of plasticparts. A family mold is a mold that forms at least two separate,distinct parts that are to be joined together to form a single product.However, a need still exists for an efficient and cost-effective processfor removing the molded parts from mold and assembling them into afinished product.

A variety of mechanisms have been used to remove the molded parts fromthe family mold, For example, in U.S. Pat. No. 4,915,611, a receiver isused to transfer the molded parts to a container. A family mold is usedto produce a number of molded articles. The receiver, having individualarticle receptors, mates with the molded articles in order to remove thearticles from the mold and transfer the molded articles from the mold toa container. U.S. Pat. No. 4,976,603 also discloses a device forremoving molded pieces from a stacked mold. A rotatable arm assemblywith a suction cup is utilized to remove the molded pieces from thestacked mold. As the mold portions are moved from close to open, the atleast one suction cup engages the molded pieces and rotates through aninety degree arc. The suction cup then releases the work piece so thatthe molded work piece is dropped down a chute to a conveyor belt.

While these patents disclose methods for removing molded parts from afamily mold, these patents do not disclose a method for not only moldingand removing the parts from the mold stack, but also assembling theseparate, distinct parts into a product and then transferring theproduct to a magazine and/or container for storage. By utilizing anautomated process that not only molds the parts but also removes andassembles the parts, the subject invention is able to cut down on themanufacturing cost associated with molding and assembling multi-pieceparts. This and further advantages will become more apparent from thefollowing description and drawings.

BRIEF INVENTION SUMMARY

The subject invention relates to the field of injection molding. Moreparticularly, the subject invention relates to precision and injectionmolding of multi-piece parts and the subsequent handling and assembly ofthe parts produced from the mold. One embodiment of the inventivemolding and assembly process utilizes a system with at least one familymold. As used herein, a family mold is a mold that forms separate,distinct parts that are to be joined together to form a single product.The family mold in this embodiment has alternating rows of mold cavitiesfor two separate and distinct parts. Thus, the two separate distinctparts are molded side-by-side to one another in the family mold. After amolding cycle is complete, the two different parts are removed from themold and transferred to a stacker so that the two separate parts havethe same configuration as they did in the family mold and areside-by-side on the stacker. In this embodiment, an unloader can be usedto remove the two parts from the family mold and can transfer the twoparts to a linear transporter. The linear transporter can then transferthe two parts to the stacker.

After obtaining the two distinct parts from the linear transporter, thestacker can rotate into a position that is directly above a pallet. Inthis position, the stacker can place the first set of parts on thepallet. After the first set of parts are placed on the pallet, thestacker can move laterally so that the second set of parts are locatedabove the first set of parts. The stacker can then place the second setof parts on top of the first set of parts. By placing the second set ofparts on top of the first set of parts, the system creates a set ofloosely assembly products.

The loosely assembly products can then be delivered to a welder. Thewelder will weld the two separate parts together to form a completedproduct. The completed products can then be transferred to and loaded ina magazine for storage. A pick and place unit with a plurality of vacuumgrip heads can be utilized to transfer the completed products to the atleast one magazine. Such a system and method can be utilized for avariety of products that require multiple pieces that need to be stackedon top of one another and welded together. For example, as explained inmore detail below, this system and method can be utilized to createsurgical suture packages with a bottom part and a top part.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a bottom view of a top part of an exemplary productcreated by the inventive molding and assembly process;

FIG. 1B shows a top view of a bottom part of the exemplary productmanufactured by the inventive molding and assembly process;

FIG. 1C shows the assembled exemplary product with the top part andbottom part joined together;

FIG. 2 shows a diagrammatic top view of a system with a dual injectionmold and stacker used to produce the exemplary part of FIG. 1C;

FIG. 3A shows a side perspective view of the dual injection mold of FIG.2;

FIG. 3B shows a side perspective view of one of the molds that comprisethe dual injection mold of FIG. 3A;

FIG. 4 shows a diagrammatic view of the system of FIG. 2 during theinjection mold cycle;

FIG. 5 shows a diagrammatic view of the manifold of the dual injectionmold of FIG. 3A;

FIG. 6 shows a diagrammatic view of the system of FIG. 2 during theunloading cycle;

FIG. 7 shows a diagrammatic view of the system of FIG. 2 during thetransfer of the top parts and bottom parts to the stacker;

FIG. 8 shows a front view of the stacker of FIGS. 2, 4 and 7;

FIG. 9 shows the stacker of FIG. 8 after the top parts and bottom partshave been transferred to the stacker;

FIG. 10 shows the stacker of FIG. 9 being rotated so that it caninteract with a pallet;

FIG. 11 shows the stacker of FIG. 9 positioned directly above thepallet;

FIG. 12 shows a pick and place unit removing fully assembled productsfrom the pallet;

FIG. 13 shows the completed products being delivered to a magazine forstorage and shippage.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1C shows an exemplary product created by the inventive molding andassembly process. As shown in FIGS. 1A-1C, the exemplary product is atwo piece riveted package 10 for surgical sutures. The product includesa top part 12 (shown in FIG. 1A) with a plurality of rivet pins 16 and abottom part 14 (shown in FIG. 1B) with a plurality of rivet holes 18.Top part 12 and bottom part 14 each also have at least one pilot hole19. When top part 12 and bottom part 14 are joined together, pluralityof rivet pins 16 extend from the top part through plurality of rivetholes 18 on the bottom part. A heating device welds rivet pins 16 sothat the pins melt into rivet holes 18 and heat stake top part 12 tobottom part 14.

FIG. 2 shows a top diagrammatic view of an exemplary system 100 used toperform the molding and assembly process of the surgical suturepackages. As shown in FIG. 2, system 100 comprises a dual injection mold20. Dual injection mold 20 is a “stacked” mold consisting of twoseparate sets of molds A and B. Each of the molds A and B produce topparts 12 and bottom parts 14. FIG. 3 a shows a side perspective view ofmolds A and B and FIG. 3 b shows a close up perspective view of mold A.As shown in FIGS. 3 a and 3 b, molds A and B each contain a plurality ofmold cavities 30 for top parts 12 and a plurality of mold cavities 32for bottom parts 14, As can be seen in FIG. 3 b, mold cavities 30 fortop parts 12 and mold cavities 32 for top parts 14 are positionedside-by-side to one another so that each of the molds A and B havealternating, parallel columns of mold cavities 30 for the tops parts andmold cavities 32 for bottom parts.

Referring to FIGS. 2 and 3 a, dual injection mold 20 comprises astationary side 22, a moveable opposite side 24, and a moveable center26. Two helical. screws 28 are positioned on each side of mold 20 andconnect stationary side 22, moveable opposite side 24, and moveablecenter 26 to one another. FIG. 4 shows a diagrammatic top view of thesystem during a mold cycle. As shown in FIG. 4, an operating means (notshown), such as an electric motor or any other means well known in theart, causes helical screws 28 to advance so that opposite side 24 movestowards moveable center 26 in the direction of arrows 34 until itcontacts the movable center. Movable center 26 also moves in thedirection of arrows 34 until it comes into contact with stationary side22. Dual injection mold 20 is collapsed such that the center 26 joins toboth the stationary side 22 and the opposite side 24 to form moldcavities 30 for the top parts and mold cavities 32 for the bottom parts.

Once molds A and B are closed, an injector 54 pumps molten plastic(shown by arrow 38) through a center port 36. Center port 36 runsthrough both molds A and B in order to till the mold cavities 30 for thetop parts and 32 for the bottom parts. Both molds A and B are familymolds because each of the molds simultaneously mold separate, distinctparts that are to be joined together to form a single product. FIG. 5shows the layout of each of the molds A and B. As shown in FIG. 5, moldsA and B each comprise a manifold 46 with center port 36. A plurality offlow channels 40 branch off of centerport 36 and a plurality of runners44 branch off of flow channels 40. At the end of each runner 44 is agate 42 that connects the runner to either mold cavity 30 or mold cavity32. Each gate 42 is associated with a pneumatic valve that opens andcloses the gate. Manifold assembly 46 allows molten plastic to pass fromcenter port 36, through flow channels 40, through runners 44, throughgates 42, and into each of mold cavities 30 and 32. Gates 42 areelectronically controlled and are selectively opened at different timesduring the mold cycle in order to control the timing of the moltenplastic entering each mold cavity, and thus ensuring that each part hasa similar density as other parts in the mold. This process of openingand closing the gates to the mold at different times is often referredto as “sequential injection” molding. Once the mold cycle is completedand top parts 12 and top parts 14 are molded, each runner 44 is pinchedoff at each gate 42 by the pneumatic valve associated with the gate. Inthis embodiment, each mold A and B produce 16 parts during a mold cycle(8 bottom parts and 8 top parts). However, it is possible to createmolds with more or less mold cavities in order to produce more or lessparts.

After a mold cycle is complete, molds A and B open and molded top parts12 and bottom parts 14 are removed from mold cavities 30 and 32. FIG. 6shows a diagrammatic top view of system 100 during the unloadingprocess. As shown in FIG. 6, helical screws 28 retreat in the directionof arrows 48 so that movable center 26 and opposite side 24 move awayfrom stationary side 22. Helical screws 28 ensure equal spacing of moldsA and B when the molds are completely open. Once molds A and B are open,an unloader 50 is inserted between stationary side 22 and movable center26 of mold A. Unloader 50 includes a plurality of vacuum grippers 52.Vacuum grippers 52 contact molded top parts 12 and bottom parts 14 andform a vacuum between the grippers and the top parts and bottom parts.In this manner, vacuum grippers 52 secure these molded parts to unloader50 in the same arrangement as they were molded in mold A (i.e., topparts 12 and bottom parts 14 are placed in four alternating, parallelcolumns so that each of the top parts is positioned next to one of thebottom parts). While only the removal of top parts 12 and bottom parts14 from mold A is shown, the removal of the top parts and bottom partsfrom mold B will be accomplished with an essentially identical process.The number and location of vacuum grippers 52 on unloader 50 correspondsto the number and location of parts produced by mold A. Thus, in thisembodiment, unloader 50 can remove and unload all 16 parts from mold Aat one time.

FIG. 7 shows a diagrammatic top view of system 100 during thetransferring process of top parts 12 and bottom parts 14 from unloader50 to a linear transporter 56 and from the linear transporter 56 to astacker 58. As shown in FIG. 7, unloader 50 is removed from mold 20 andinterfaces with linear transporter 56 so that the linear transporterreceives top parts 12 and bottom parts 14 from the unloader. Lineartransporter 56 also has vacuum grippers 52 that correspond in number andlocation to the vacuum grippers located on unloader 50. Lineartransporter's 56 vacuum grippers 52 contact and form a vacuum on toppails 12 and bottom parts 14 of unloader 50, while the vacuum is removedfrom unloader's 50 vacuum grippers in order to release the top parts andbottom parts. The parts are arranged on linear transporter 56 just asthey were molded within molds A and B (i.e., top parts 12 and bottomparts 14 are placed in four alternating, parallel columns so that eachof the top parts is positioned next to one of the bottom parts). Duringthe time that unloader 50 places the parts on linear transporter 56,dual mold 20 collapses and molten plastic 38 is again delivered to themolds A and B and the molding process begins again.

Still referring to FIG. 7, linear transporter 56 moves along a path 60and delivers top parts 12 and bottom parts 14 to stacker 58. FIG. 8shows a front view of stacker 58. As shown in FIG. 8, stacker 58includes a plurality of vacuum cups 62 for holding top parts 12 andbottom parts 14. Referring back to FIG. 7, linear transporter 56 movesalong path 60 until top parts 12 and bottom parts 14 come into contactwith vacuum cups 62, When stacker 58 receives parts from the lineartransporter, it is in a vertical position. Vacuum cups 62 form a vacuumon top parts 12 and bottom parts 14 while the vacuum from the vacuumgrippers 52 of linear transporter 56 is removed to release the top partsand bottom parts. Vacuum cups 62 are arranged on stacker 58 so that topparts 12 and bottom parts 14 are held on the stacker in the same patternas the parts are held on linear transporter 56, 9 shows stacker 58 aftertop parts 12 and bottom parts 14 are transferred to stacker 58 fromlinear transporter 56. As shown in FIG. 9, top parts 12 and bottom parts14 are positioned in four alternating, parallel columns of top parts andbottom parts, so that each top part is positioned next to one of thebottom parts.

Still referring to FIG. 9, stacker 58 is positioned on a shaft 64 thatcan be rotated 360 degrees in both the clockwise and counterclockwisedirection by an electrical motor or a variety of other means well knownin the art. After receiving top parts 12 and bottom parts 14 from lineartransporter 56, shaft 64 and stacker 58 rotate 90 degrees, so that thestacker is in a horizontal position and interacts with pallet 66. FIG.10 shows shaft 64 and stacker 58 being rotated so that the stacker caninteract with pallet 66. As shown in FIGS. 7 and 10, pallet 66 includestwo distinct rows of assembly nests 70. Each assembly nest 70 containstapered pilot pins 72 that are designed for insertion into pilot holes19 of top parts 12 and bottom parts 14. Pilot pins 72 also contact theedges of the top parts and bottom parts. In this manner, pilot pins 72interacts with top parts 12 and bottom parts 14 in order to align thetop parts with the bottom parts. FIG. 11 shows stacker 58 positioneddirectly above pallet 66. As shown in FIG. 11, stacker 58 rotates untilit is positioned directly above pallet 66 in a horizontal position andtop parts 12 are directly over assembly nests 70. Once stacker 58 is inthis position, it releases top parts 12, so that each top part fallsfrom the stacker and is received in one of assembly nests 70 of pallet66. As top parts 12 are released, pilot pins 72 engage the edges of toppart 12 and are inserted into pilot holes 19 of the top part. In thismanner, pilot pins 72 ensure that the top part is accurately positioned.

Still referring to FIG. 11, stacker 58, next, shifts in the direction ofarrow 74 so that bottom parts 14 are positioned directly over assemblynests 70 and top parts 12. Stacker 58 then releases bottom parts 14 sothat each bottom part falls from stacker and is received in one ofassembly nests 70 of pallet 66. In each assembly nest 70, pilot pins 72engage the edges of bottom part 14 and pass through pilot hole 19 toensure that the bottom part is accurately positioned on top of top part12, so that the top parts' rivet pins 16 extend through the bottompart's rivet holes 18 and are exposed upwards. In this manner, top parts12 and bottom parts 14 are loosely assembled into packages 10 ofsurgical sutures.

Referring back to FIG. 7, once packages 10 are loosely assembled, pallet66 proceeds along conveyer belt 80 and passes under ultrasonic welders82. After pallet 66 proceeds to ultrasonic welders 82, shaft 64 andstacker 58 rotate back to their original position so that the stackercan receive the next load of top parts 12 and bottom parts 14 andanother pallet 66 is put in, position. Stacker 58 then repeats theabove-described process to loosely assembly packages 10 on the newpallet.

Still referring to FIG. 7, pallet 66 travels down the conveyor belt 80until it comes to a position below ultrasonic welders 82. Ultrasonicwelders 82 descend over loosely assembled packages 10 with their hornsbearing on protruding rivet pins 16. In this manner, ultrasonic welders82 melt rivet pins 16 down into rivet holes 18 and heat stake the bottompart 14 to the top part 12. Pallet 66 then moves past ultrasonic welders82 along conveyer belt 80 into a position that allows assembled packages10 to be removed from pallet 66 and stacked in a magazine for storageand subsequent shipping,

FIG. 12 shows a pick and place unit 90 removing fully assembled packages10 from pallet 66. As shown in FIG. 12, pick and place unit 90 has aplurality of vacuum grip heads 92 that contact and form a vacuum on eachof the packages 10. Pick and place unit 90 then removes each package 10from each assembly nest 70 at the same time. FIG. 13 shows pick andplace unit 90 delivering completed packages 10 to magazine 94. As shownin FIG. 13, each magazine 94 has four slots 96 that are each dimensionedto receive four completed packages 10 at the same time, Also shown byFIG. 13, pick and place unit 90 has enough vacuum heads 92 to place fourrows of four packages (total of 16) in magazine 94, Pick and place unit90 loads packages 10 into each of magazine's 94 slots 96 by releasingits vacuum grip on packages 10. Pick and place unit 90 repeats thisprocess of transferring the packages 10 from pallet 66 and depositingthe completed packages on top of each other in the magazine's slots 96(visible suture package stacks are shown in FIG. 13) until the magazine94 is filled.

While a particular embodiment of the subject invention has beendescribed in considerable detail herein, such is offered by way of anon-limiting example of the invention as many other versions arepossible. For example, molds A and 13, unloader 50, linear transporter56 and stacker 58 can be constructed to mold, produce, hold andtransport any number of molded parts. Further, packages of surgicalsutures do not have to be the product molded and assembled using thisprocess. Rather, any product or package that requires any number ofseparate molded parts to be molded, stacked and assembled to one anothercan be manufactured by this process, Moreover, pallet 66 and pick andplace unit 90 can be constructed to hold and transport any number ofassembled products. It will also be appreciated by one skilled in theart that pallet 66 could be laterally shifted instead of stacker 58 inorder to loosely assembly the top part 12 and bottom part 14 into apackage 10. It is anticipated that a variety of other modifications andchanges will be apparent to those having ordinary skill in the art andthat such modifications and changes are intended to be encompassedwithin the spirit and scope of the appended claims.

We claim:
 1. A method of assembling multi-piece parts to form a product,the method comprising the steps of: (a) providing a plurality of topparts and a plurality of bottom parts side-by-side on a stacker; (b)positioning a pallet adjacent to the stacker; (c) rotating the stackerso that the stacker and the top parts and bottom parts are located abovethe pallet; (d) placing each of the top parts onto the pallet; (e)laterally shifting the stacker; (f) placing each of the bottom parts ontop of the top parts to form a plurality of loosely assembled partsdisposed on the pallet; and (g) joining the plurality of looselyassembled parts to form products.
 2. The method of claim 1, furthercomprising the step of molding the top parts and bottom parts in afamily mold.
 3. The method of claim 2, wherein the top parts have aplurality of rivet pins on each of their surfaces and the bottom partshave a plurality of rivet holes and wherein the step of placing eachbottom part on top of each top part further comprises inserting therivet pins into the rivet holes.
 4. The method of claim 3, furthercomprises the step of melting the rivet pins with at least one welder sothat each top part and bottom part are heat stacked to one another toform completed products.
 5. The method of claim 4, further comprisingthe step of transferring the completed products to a magazine andloading the completed products in the magazine.
 6. The method of claim5, wherein at least one pick and place unit with a plurality of vacuumgripers is utilized to transfer the completed products to the magazine.7. The method of claim 6, wherein at least one unloader and at least onelinear transporter are utilized to transfer the top parts and bottomparts to the magazine.
 8. A system for molding and assemblingmulti-piece parts to form a product comprising: (a) at least one familymold that molds a first plurality of parts and a second plurality ofparts positioned side-by-side to one another; (b) at least one stackerthat rotates and moves laterally with a plurality of vacuum gripers thatcan interact with the first and second plurality of parts in theside-by-side orientation; (c) at least one pallet arranged andpositioned adjacent to the at least one stacker so that when the stackerrotates, the stacker will be directly above the pallet so that the firstplurality of parts can be placed on the pallet and when the stackermoves laterally the second plurality of parts can be placed on the firstplurality of parts on the pallet to form a plurality of looselyassembled parts disposed on the pallet; and (d) at least one device forjoining the first and second plurality of parts to form products.
 9. Thesystem of claim 8, further comprising at least one moveable unloaderthat interacts with the family mold to remove the first and secondplurality of parts.
 10. The system of claim 9, further comprising atleast one moveable linear transporter that can interact with theunloader to obtain the first and second plurality of parts and transferthe first and second plurality of parts to the stacker.
 11. The systemof claim 10, further comprising a conveyor belt that interacts andtransports the pallet.
 12. The system of claim 11, wherein the at leastone device for joining the parts is at least one welder that can weldeach of the first plurality of parts to the second plurality of parts tocreate completed products.
 13. The system of claim 12, furthercomprising a pick and place unit that can remove the completed productsfrom the pallet.
 14. The system of claim 13, further comprising amagazine that can hold and store the completed products for shipping.15. The system of claim 8, wherein the pallet comprises a plurality ofassembly nests each with at least one pilot pin that properly aligns thefirst plurality of parts with the second plurality of parts.